Die collapsed anchor nut



Feb. 23, 1954 C, T, TORRESEN Er AL 2,670,021

DIE COLLAPSE@ ANCHOR NUT Filed June 3. 1949 INVENToRs Ma Z oefff/v Aw W/z//W Kimm/#puff Patented Feb. 23, 1954 DIE COLLAPSED ANCHOR NUT Carel '.T. Torresen, Santa Monica, and William V. .Stackhousa Torrance, Calif.

Application June 3, 1949, SerialL-No.'9.6,954

'-7 Claims. 1 This invention relates to threaded fastening devices and particularly to the class of nuts `generally known `as anchor nuts and widely lused in ythe aircraft industry.

Several different ygeneral types rof r`anchor nuts have been used -for some time and each has `advantages and disadvantages. One type, commonly known by Ythe ytrade name Riv-Nut, comprises essentially va .tubularbarrel having an enlarged head-at one end and an 'internal thread- `ed bore at the other. To fasten it in position in 'an aperture ina-sheet of metal, lit is nrst inlserted until the 'head contacts the sheet.

because only a limited .force can 'be applied. Forces high enough to produce a .satisfactory grip would result in failure of the pull-rod tension or vfailure of the threads in shear. `VConsequently, to prevent rotation when ,a "bolt or screw is inserted, it is usually necessary .to :pro-

vde the anchor nut head with -a small 'bossserv- 'ing as a detent, this boss 'ttingintola radial .key slot in the sheet iin conjunction with vthe :aperture. This, of course, .requiresadditional special '.tools, and the detentstill .sometimes works out of the key slot because `the rgrip is .not tight enough.

Another type, lquite `commonh7 fused, .comprises ,a rnut Ybody Ahavingone or two integral wings vextending radially.outwardlytheretrom. vEachwing hasvan aperture therein v.and the z'nut is 'anchored 4to ,a Ysheet by riveting the wings thereto. This type can take yextremely lhigh torques land :can readily be yprovided 4with vulcanizedrber jlocking means. It has the disadvantage of .requiring a relatively large :space ,for installation fand also 'reyquires 'the drilling of two rivet'holes as well as the bolt hole, :plus the drivingfof -ltwo rivets. All three holes must be 'carefully aligned so that the -nut -will register properly with the bolt hole.

The anchor nut iof the present invention obviates the disadvantages mentioned above. *It -is lgenerally similar :to l-the i'lrst vtype described ybut nis provided with -a shoulder` on the rexteriorcf `=the barrel between I`the Athreaded boregand Ethe enlarged head. lWith this construction it is possible 4'to use squeezing tools to iprovidethe bulging action and to exertenough-axial'pressure -to produce "the necessary tight squeeze l-lavetween the f 2 bulge Vand 'the head so `that the nut can .resist torque without rotation.

vSince the shoulder is `s'hortof the threads, they are not distorted in lthe squeezing operation. 1f it is desired to use detent means to handle maximum torques the squeezing fforces can be high enough to locally deform the mounting sheet to conform to the ldetent 'onfthe nut and `consequently no special tools are `necessary to preform a 'key-'slot or the like in theisheet it vis desiredto use akey-slot in-the sheet, the squeezing forces can be high enough to l deform f aporvtion of` the nut intoithe slot.

The anchor nut vof 4lthe present finventiomaccomplishes Aa mounting ias `secure as that of fthe `second type described above -and takes yup "lconysiderably less space 'by-eliminating the mounting wings. It `also eliminates the extra mounting holes and rivets and weighs substantially less per unit, which is of Iextreme `importance in aircraft work, where every pound which goes into structure decreases the pay load by a Apound.

Since the new `anchor nut exerts a very high squeeze it can serve the dualpurpose of fasten- `ing "two or more structural sheets together'without added weight or duplication. The first type mentioned above is ynot well suited to this puripose because it Vcannot be made tight enough, andthe second type requires, of course, the useof two or'more conventional rivets.

lThe novel anchor nut in rseveral of its presently preferred forms, as Well as the-method of mounting, are illustrated lin the accompanying drawing, infwhich z Figure 1 is a ysectional elevation of the novel `anchor nut Vprovided with `a spring lgrip thread lock;

Figure v2 is an elevational View, partly in sec- -tion,o'fthe novel anchor nutinserted'intoa dim- 'pled sheet Aof metal Kand squeezed intoanchoring positionby a vpair 'of axially compressive dies;

rFigure 3 :isa View 'similar lto Figure -1, showing a vulcanized nbertype'of thread lock; Figure Liis a aperspective view of a portion of ametal sheet 4having a -dimpled `aperture therein and `a key slot connected with said aperture;

Figure 5 is a perspective view o'f an upper `die member provided v`Withspecial means for deforming a part of fan anchor 'nut into the lkey -slot vof Figurei Figure -6 is yan elevational View, partly 4in l'section showing an -anchor'nut inserted in the -sheet fof Figure -4 and squeezed into gripping `engagement, a lportion of the ynutbo'dy being forcedlintc `-the-key'slot;

used generically herein.

Figure 7 is a perspective view of a modied form of the anchor nut with a detent forming slot in its head;

Figure 8 is an elevational view, partly in section, showing the nut of Figure 7 anchored in a sheet, a portion of the latter being forced into the detent slot of the head;

Figure 9 is a perspective view of another modiiied form of the nut with an upstanding detent boss on the under side of the head;

Figure 10 is an elevational view, partly in section, showing the nut of Figure 9 anchored in a sheet, a portion of the latter being deformed around the detent;

Figure 11 is a sectional elevation of a further modified form of the novel anchor nut;

Figure 12 is an elevational view, partly in section, showing the nut of Figure l1 anchored in a sheet, and a bolt attached to the nut and holding a second sheet in place;

Figure 13 is a sectional elevation of a further modined form of the novel nut;

Figure 14 is an elevational view, partly in section, showing the nut of Figure 13 inserted in a dimpled sheet and squeezed into anchoring relation by a pair of special dies; and

Figure 15 is a `sectional view of the joint of Figure 14 with a second dimpled sheet attached thereto by a iiush screw.

The anchor nut illustrated in Figure 1 includes a tubular barrel i6 of substantially uniform diameter having at one end an enlarged head Il, here shown as conical or ush type, tho it may have any other desired form, and at the other end a portion I8 of reduced diameter producing a shoulder it. The reduced portion has a threaded bore 2i of smallerl diameter than the bore 22 oi the main body and is adapted to receive a threaded bolt or other fastening. The free end of portion I8 is slotted at 23 and the sections are deformed slightly inwardly to provide a. spring grip thread lock.

It will be noted that the shoulder I9 is axially aligned with the wall of barrel it, at the opposite end of which is a flat face 2d. When pressure is applied to shoulder I3 and face 24 by axially directed coacting dies, the bursting force tends to swell out the medial portion of the lbai-rel. To insure that no deformation occurs in the threaded portion the nut is so formed that the Wall at point 2E is thicker than the wall of the barrel.

To practice the invention, the nut is inserted in a dimpled aperture 2l in a sheet 28 of aluminum alloy or other suitable material. While the sheet is shown thruout the drawings as being relatively thin, the novel anchor nut is capable of use with any of the sheets or plates used in aircraft construction and the term sheet is The nut is supported in place by a die 29 having a pilot pin 3|, and a second die 32 having a bore 33 and a counterbore 3a, providing between them a shoulder 33, is applied to the upper end of the nut. Shoulder 36 engages shoulder it of the nut and the bore 33 provides axial clearance for the portion I3. The lower free end of the die is belled out at 31. The dies are, of course, mounted in a squeezer of any known type and in operation they are moved axially toward each other with great force to collapse the nut barrel Iii axially and expand or bulge it radially, the bell mouth 3? forcing the bulge 38 downwardly in conical fashion against the opposed face of the dimple to anchor the nut securely in the sheet. The vpermanent 4 axial compressive force is sufcient to resist low and medium torques. It will be apparent that the nut as just described will readily join two or more sheets in a permanent and satisfactory manner.

The nut shown in Figure 3 is substantially identical in construction and operation to that of Figure 1 but the upper portion 39 is recessed to receive a vulcanized ber ring t! and is peened over at Q2 to hold the ring in place to provide an elastic thread lock.

In the event that the anchorage of the nut is to be subjected to relatively high torques several forms of positive detent means are contemplated. The sheet of metal d3 in Figure 4 is provided with a dimpled aperture 44 having a key slot it extending radially outward therefrom. The nut of Figure 1 is inserted in the aperture and a special die 41 shown in Figure 5 is used to provide the lockingeect. This die is provided, on its lower face 48 with a narrow, axially projecting and radially extending boss di) of approximately the same width as slot 4S.

When the nut is assembled in the sheet and placed on lower die 5I, the upper die is placed over the free end of the nut and axial force is applied as previously described, with the boss 49 in alignment with slot lit. As the barrel becomes fully collapsed the boss t9 pushes a portion 52 of the bulge into slot d6 to provide a positive interlock; preventing any rotation in the jointure.

The use of a key slot such as 1S requires a special notching tool to be used separately in making every jointure. To obviate the need for the special tool, detent forming means are provided in the head 53 of the nut 5d shown in Figure 7. This detent takes the form of a radial slot or saw cut 5t. This nut is assembled with dimpled, apertured sheet 51 and the dies 41 and 5l are applied to the assembly in the same manner as in Figure 6. As illustrated in Figure 8, the boss t9 will depress a portion of the bulge 58 which, in turn, will force a portion 59 of the sheet down into slot 55 and produce a permanent, rotation-proof anchorage.

Instead of using a slotted head the nut 8i of Figure 9 has a head t2 on the inner face of which is formed an axially protruding radially extending detent boss 63. The head in this case is shown as flat although the type of head is a matter of choice. This nut is assembled with an apertured sheet 6A and placed on lower die 5|. An upper die 65, of the same general type as the previous ones but provided with a radially extending depression 61 is placed on the upper end of the nut and squeezing pressure is applied. The majority of the bulge is forced down against the flat portion of the head E2, but the portion 68 of the sheet is deformed upwardly around the boss 63, at the same time deforming a part of the bulge upwardly into recess 67, to produce a torque-resisting, interlocking configuration.

'I'he type of nut so far described provides a generally satisfactory connection for an attachment bolt. However, in some instances it is desired to provide bearing support for a bolt adjacent to the surface of the sheet to which the anchor nut is attached. A modication which accomplishes this result is illustrated in Figure 1l in which the nut body 69 is similar in all respects to the nut of Figure 1 except that the bore at the head end 'Il is decreased at 'i2 to a diameter corresponding to the shank diameter of the bolt to be used therewith. As seen in Figure 12 the y.nut is anchoredvin sheet 13, and bolt 74 is snugly aevogoei received ltherein, holding an .additional sheet 16 in 'place by means .of .head 1.1. rSince the 'bolt :is rmlyfsupported adjacent .both of its ends, there will'be no llateral .shifting .of the sheets -with krespect 'to each other. It will be obviousthat vthis feature maybe .applied to all .forms of the invention disclosed herein.

The nut 'iS, shown in Figure 13, is particularly suited to v`installations in which it is desired to attach an outer sheet to an inner sheet and maintain a smooth, flush outer surface. The nut has aiconical head i9 with a conical counterbore 3l terminating in an annular flat seat 82 directly axially opposed `to shoulder dit. When the nut is assembled `with sheet 8A it -is mounted -on 'lower die 86, Figure 14, which has a tapered pilot pin 8l with a flat upper surface 88 ci such diameter as to provide direct contact with seat 82 and axial opposition to compression loads on shoulder 83. The die 89, having a core 9i and counterbore 92 forming seat 93, is placed over the upper end oi nut iti and compression loads applied as in the previous instances. Since the seats 88 and 93 are directly opposed there is no force applied to head i9 to distort it from its desired shape.

When the jointure is completed there is provided a threaded aperture with a conical counterbore. Consequently, as seen in Figure 15, a second dimpled sheet @il may be laid snugly against sheet trl and held in place by bolt Si@ having a iush head 9i, providing the smooth contour needed for aerodynamic installations.

In all forms of the invention the internal threading of the nut is substantially confined to the reduced portion beyond the compression shoulder. Hence the distorting forces will have no effect on it. The threads are further proe tected against any possible distortion by the thickened portion indicated at 2li in Figure l. Moreover, the counterbore in the upper die also assists in maintaining the shape of the upper end of the barrel during the compression operation.

If it is desired to use the nut in installations requiring a uid tight connection it can be formed with the upper, or reduced, end closed although the locking feature Will have to be sacrificed.

While the presently preferred forms of the invention have been illustrated and described in detail, it will be apparent to those skilled in the art that various changes and modifications may be made in the construction and method of application Without departing from the spirit of the invention and it is intended that all such changes and modifications shall be embraced within the scope of the following claims.

We claim:

l. An anchor nut comprising: a generally cylindrical barrel having substantially uniform internal and external diameters thruout the major portion of its length; said barrel having a smooth cylindrical bore throughout said major portion, an enlarged head formed adjacent one end thereof; the opposite end of said barrel being of reduced external diameter to form a shoulder engageable by a force-applying tool; said portion of reduced diameter having a threaded bore of smaller diameter than the bore of the intermediate portion oi said barrel; said intermediate portion of said barrel having a greater crossseetional area than said portion of reduced diameter, producing substantially greater resistance to axial compression failure and radial collapse than said portion of reduced diameter.

2. An anchor :nut :comprising: -a Igenerally Ycylindrical barrel portion having'sa `substantiallt7 uniform 'external diameter; an enlarged head at one end ofv said barrel portion; a second cylindrical portion extending axially from the opposite lend of said barrel portion `and :having =an external diameter .less than that :of said barrel portion ,to provide an external shoulder engageable 'by a force-applying tool; said second ;por tion having an internal ythreaded bore vof less diameter than the bore of said `barrel portion extending slightly beyond 4said `shoulder toward said head to produce -a Atransition section Aof greater cross-sectional area ythan ythat of either the first ror second cylindrical portions; vwhereby axial compression pressure applied to said shoulder will produce a bulge intermediate the length of said barrel portion without distorting the threaded bore.

3. An anchor nut comprising: a first generally cylindrical, barrel portion having substantially uniform internal and external diameters thruout its length; an enlarged head at one end of said barrel portion; a second barrel portion in continuation of said first barrel portion having substantially the same external diameter and having a substantially smaller inner diameter; a third barrel portion in continuation of said second barrel portion having a smaller external diameter than said second barrel portion to form an external shoulder engageable by a force-applying tool and having an internal diameter substantially equal to that of said second barrel portion; and an internal thread formed in said second and third barrel portions; said rst barrel portion having a greater cross-sectional area than said third barrel portion; and said second barrel portion having a greater cross-sectional area than said rst barrel portion.

4. An anchor nut as claimed in claim 3; said third barrel portion being provided with thread locking means at its outermost free end.

5. An anchor nut as claimed in claim 3; said enlarged head portion having a bore of smaller diameter than the inside diameter of said first barrel portion to serve as a bearing for the shank of a threaded member inserted in the second and third barrel portions.

6. An anchor nut as claimed in claim 3, said enlarged head portion having a flared outer Wall to seat in a conical depression in a structural member and having a rusto-conical countersink formed therein to receive a complementary portion o another structural member.

7. An anchor nut comprising: a rst, generally cylindrical, barrel portion having substantially uniform internal and external diameters thruout its length; an enlarged head at one end of said barrel portion; a second barrel portion in continuation of said first barrel portion having substantially the same external diameter and having a substantially smaller inner diameter; a third barrel portion in continuation of said second barrel portion having a smaller external diameter than said second barrel portion to form an external shoulder engageable by a force-applying tool and having an internal diameter substantially equal to that of said second barrel portion; and an internal thread formed in said third barrel portion; said rst barrel portion having a greater cross-sectional area than said third barrel portion; and said second barrel portion CAREL 'I'. TORRESEN. WILLIAM V. STACKHOUSE.

References Cited in the :01e of this patent UNITED STATES PATENTS Number Name Date Rosenfeld July 11, 1916 Gruber Dec. 11, 1917 Post Oct. 15, 1935 Huck Feb. 11, 1936 Campbell et al Jan. 24, 1939 Bettington Feb. '7, 1939 Number Number Name Date Buck Feb. 28, 1939 Waner Feb. 28, 1939 Waner Jan. 30, 1940 Wallace May 18, 1943 Eklund Jan. 1, 1946 Gill Oct. 15, 1946 Huck Apr. 12, 1949 Selden July 31, 1951 FOREIGN PATENTS Country Date Great Britain Oct. 16, 1935 Great Britain June 25, 1936 Great Britain May 19, 1941 

